Graphene Oxide (GO) Based Coated Geopolymeric Membrane for Concentrating Orange Juice through Forward Osmosis

Abstract

Dewatering of fruit juice through forward osmosis (FO) has attracted great attention in recent years; however, its application for fruit juice concentration through FO is limited due to high fouling rate, low flux, and expensive nature of membranes. Inorganic membranes are expensive due to heat-intensive steps and expensive raw materials that are involved in its synthesis, while geopolymerization technique for inorganic membrane synthesis reduced the cost due to its sintering-free steps and using fly ashes as a source material. In this research work, we report sintering-free economical and eco-friendly geopolymeric membrane in FO pilot-scale plant for orange juice concentration. However, the low flux of geopolymeric membrane was enhanced through coating of graphene oxide (GO) layer for high hydrophilicity. In this work, water flux through GO-based coated and uncoated geopolymeric membrane for concentrating sugar solution through FO was investigated. Prepared GO was coated on geopolymeric substrate through spin technique. The pore size of both geopolymeric substrate and GO was 1.8 and 5 µm, while porosity was 51.09% through the gravimetric method for both active and supportive layer. The orange juice solution was concentrated to 26.1 ± 0.5° and 21.87° Brix from 15.2 ± 0.5° Brix reaching flux of 0.405 and 0.360 kg.m−2.h−1 at a temperature of 30°C using sodium chloride salt solution (10 M) by coated and uncoated geopolymeric membranes, respectively. This study indicates that GO-based coated geopolymeric substrate is an eco-friendly and cost-effective feasible approach for fruit juice concentration through FO application.